A connector apparatus of the present disclosure is configured to include: a waveguide cable; a substrate including a waveguide structure; and a coupling section configured to electromagnetically couple an end portion of the waveguide cable to the waveguide structure. Furthermore, a communication system of the present disclosure is a communication system including: a transmitter configured to transmit high-frequency signals; a receiver configured to receive high-frequency signals; a waveguide cable configured to transmit high-frequency signals between the transmitter and the receiver; and a connector apparatus configured to connect between at least one of the transmitter and the receiver to the waveguide cable. A connector apparatus having the above-mentioned configuration is used as the connector apparatus.